I'm sorry I don't have any *advice*, but this is kinda what's happening with my Duchess right now. She came to me (in February) on mice, and she pooped every couple of weeks (so not as often as your snake I guess). Then, since she's good-sized, I thought, why not move her to small rats? So she took one...then a second one a week and a half or so later...no poop. Then she started refusing every rat I put in there, for over a month. Then I offered a mouse and she took it. *Then* she pooped. O_o So, I dunno. It's almost like rats don't make her poop, lol. Anyays, yes, she did in fact get "irregular" when I switched her from mice to rats. Weird.